I have a 98 Honda Accord and a couple weeks ago, I had a flat tire in the front and after my dad repaired the tire (noticed there was more wear on the inner part of the tire), I noticed that the steering is somewhat shaky when you drive over 70 mph and it wasn't like this before. What could the problem be?

 

Your tire is no longer balanced on the wheel, or the wheel is bent.

 

OK thanks, probably needs a tire balancing. I heard tires should be balanced whatever you repair or get new tires, is that true?

 

Yes.

 

Tie rods could help a TON.
If there loose, you could have weak to strong amounts of play, making it easier for things to shake. Cheap fix. Then get an alignment, which probably needs to be done by now, assuming you're an average person like me...